Improvement in pulley-blocks



" block.

PATENT HENRY F. SHAW, OF WEST ROX-BURY, ASSIGNOR TO JAMES A. WOODBU] AND SOLOMON S. GRAY, OF BOSTON, MASSACHUSETTS.

INI PROVE'M ENT IN PU LLEY-BLOCKS.

To alljwhom fit may concern:

' Be it known that I, HENRY F. SHAW, `of West Roxbury, in the county of Norfolk and State of Massachusetts, have invented a new and useful Improvement in Pulley-Blocks, of which the following is a full, clear, and exact description, reference being had to the acco1npanying drawings, making a partof this speciiivcation, in which- Figure l represents a perspective view of a pulley-block embodying my invention. Fig. 2 is a transverse vertical section of the saine, and Fig. 3 is a section on the line w y of Fig. 2. Fig. 4 is an end view of the eccentricsleeve.

The object of my invention is to produce a pulley-block which will be very simple in its construction, eii'ective in operation, and capable of sustaining aweight at any desired height without the aid of a ratchet and pawl orl any other holding device, and also to dispense with thev use of a lower or 'secondary sheath.

The nature of my invention consists in the application to the construction of a pulleyblock of a differential gear, as described in a patent granted to me March 10, 1868, and num l. bered 7 5,304, in which two wheels, having, re-

spectively, an external and internal'gear, are hung eccentrically upon a shaft, which is free to revolve independently of either gear.

lIn my present invention the gears are arranged upon an eccentric-sleeve,y which is keyed to the shaft that passesl into or is journaled in the two sides or frame of a pulley- Upon the same shaft that bears the eccentric-sleeve is secured the winding-wheel, by -which the shaft and eccentric are rotated.

To the pulleys connected with the gears are attached .cords or ropes, which sustain the weight to be lifted, one end being attached to the pulley connected to the internal, and the other to that connected to the external gear, so that, as the eccentric-sleeve is rotated, the pulleys will act mutually as buttresses, and

thus overcome any resistance offered to the tendency to relative motion.

Both pulleys being free upon the actuati sleeve or shaft, and the two ropes drawing opposite directions, a perfect equilibrium tension is maintained.

Referring to the dra-wings, A representsi frame of la pulley-block, provided with '1 `swiveled hook B. O represents a shaft orb passing through or hun g in, the sides of i frame. On the shaft G placed a sleeve, c sisting 'of a cylindrical portion, 1, upon whi is secured the winding-wheel D, carrying t rope h. 2 and 3 are eccentrics formed on c posite sides of the sleeve. The ends of t' ropes, e and f, are attached, respectively, the pulleys E and F, and the other ends the swiveled hook G, that sustains the weig H. The pulley E carries theinternal and t pulley F the external gear.

Upon putting the driving-wheel in moti by pulling the rope h, the eccentric-sleeve w be rotated, and as the two gears moven( pendently of the eceentric-sleeve,. and are sisted in their lmotion by an equal force, th will revolve slowly in opposite directions, a thus Wind up the cords that sustain the weig to be raised.

The collar is made separate from the actu: ing-shaft, so as to admit 'of its being easily i serted between the sides of the pulley-blo frame.

Having thus described my invention, wh I claim as new, and desire to secure by Li ters Patent, is

' Thev combination, in` a vWilley-block, of t windingwheel D, the differential gear, pulle E F, and an eccentric-sleeve, substantially and for lthe purpose set forth.

In testimony whereof I have signed my nai to this specification in the presence of two su 'scribingwitnesses HENRY F. SHAW.

Witnesses:

J H. ADAMS, E. L. DYER. 

